At about 15:25 EST, an Aero Commander 500 crashed after departure from Georgetown County Airport. IMC prevailed but the pilot was not instrument rated and had not filed a flight plan. The pilot and passenger were killed. A friend of the pilot stated the pilot had purchased the airplane recently and obtained a multiengine rating. The pilot and his father-in-law flew up VFR from Orlando, Fla., that morning, completing the trip through an area where the ceiling was about 600 feet. The three had lunch and the pilot said they were going to return to ORL that afternoon. The friend tried to convince him to stay until the weather improved. After changing his mind several times, the pilot departed even though the AWOS reported the ceiling at 500 feet. When the airplane reached the end of the runway over an industrial park, it encountered IMC and disappeared from view. The airplane was heard to make a left turn, and engine rpm increased. A hunter observed the airplane in a nose-down attitude, inverted, with the right wing turned up a little when it disappeared behind some trees and crashed.